Pre-forms comprising resin and fibres are known in the prior art.
U.S. Pat. No. 6,139,942 discloses a pre-form with a stack of partially impregnated fabric and un-impregnated fabric. The layers of such a stack may slide before curing and may hence be difficult to handle. It is suggested to use cross-ply stitching to prevent this. However, this process is tedious and may introduce undesirable restrictions to the shape of the stack during curing.
EP 0 475 883 also discloses a pre-form with a plurality of oriented fibre layers. However, the pre-form requires infusion of a resin to cure which may be time-consuming and to some extent prevent rearranging of the fibres and resin during curing.
WO 02/090089 discloses a moulding material having a ventilating structure in the otherwise continuous resin layers. The ventilating structure is designed to allow gas to be removed from the moulding material during processing in the plane of the resin and/or in the plane of the reinforcement material. As the ground plan of the moulding material increases, this will become a still less safe way to remove gas from the moulding material due to the increasing risk of plugging during processing.
EP 0 033 224 concerns a material for forming fibre reinforced structures with a thermoplastic resin. The thermoplastic resin is provided by passing the fibres through a bath with thermoplastic resin or by mixing dry fibres with thermoplastic fibres and heat the collection From these coated fibres is formed a fabric by weaving or knitting. The description specifically teaches away from the use thermosetting resins.
EP 1 145 841 concerns a material consisting of “fibre bundle layers.” Each fibre bundle layer consists of apparently fully wetted fibre bundles and thermosetting resin and the individual layers are oriented so that the fibres of different layers are oriented differently.
DE 198 09 264 concerns a material consisting of a number of fibre layers, each layer having an individual orientation, and a melting adhesive. The preferred and only described melting adhesives are thermoplastic adhesives (“Schmelzklebereblide aus thermoplastischem Polymermaterial”, page 3, lines 3-7).